Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations by disclosing the guessable-code exposure risk, one-hour idle expiry, free beta/no account status, the five-per-day per-network limit, and the request_id retry contract. These are non-obvious traits an agent must know before calling.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Five dense sentences, all carrying distinct information, with the core purpose and return shape front-loaded. Slightly packed but no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, the description still summarizes the return (short preview URL, four digits, one-hour idle expiry, instructions) and covers limits, retries, and safety. Everything needed to call it correctly is present.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100%, so the baseline is 3; the description adds real value by explaining request_id must be a fresh random UUID and reused with the same URL for retries, and by warning against private URLs/tokens. Minor gap: it doesn't restate the UUID pattern, but the schema covers that.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Shorten a public website') plus the target context (TV remote, console browser, phone, computer), which clearly differentiates it from the sibling get_service_info.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly names both the appropriate case ('temporary device handoff') and the exclusions ('not permanent bookmarks, private links, casting or sign-in transfer'), plus rate-limit behavior, leaving nothing to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.